A Beijing modern IX35 off-road vehicle with a mileage of about 63 thousand km and a 6 speed hand in one A6MF1 transmission. User reaction: the right steering indicator of the car is not bright. After taking the car: the inspection is consistent with the user description. The reasons for the failure are: (1) turning to the damage of the light bulb; 2. Circuit breakage or short circuit; (3) the switch damage of the steering lamp; (4) the failure of the BCM body control unit. Open the right turn light with the multimeter measured voltage 0, indicating that the steering lamp plug has no power supply, the fault point is in front, check the fuse normal, the output voltage of the steering light combination switch M20-L is about 12V, indicating the turn light switch is good, initially suspected is the BCM body control unit fault, but the replacement after the failure is still. The line of BCM plug MB-C to indoor junction box SJB is checked, and it is preliminarily determined as short circuit and open circuit of indoor junction box (I/P-D) to rear right turn light line. After cleaning the line, the wiring harness of the steering light is found to be broken by the fastening screws of the seat belt, and the steering lamp is restored to normal after being processed.